#include "Mystdio.h"
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

#define FILE_MODE 0666

_FILE * _fopen(const char *filename, const char *flag)
{
  assert(filename);
  assert(flag);
  
  int fd = -1;
  if (strcmp(flag, "w") == 0)
  {
    fd = open(filename, O_CREAT|O_WRONLY|O_TRUNC, FILE_MODE);    
  }
  else if (strcmp(flag, "a") == 0)
  {
    fd = open(filename, O_CREAT|O_WRONLY|O_APPEND, FILE_MODE);
  }
  else if (strcmp(flag, "r") == 0)
  {
    fd = open(filename, O_RDONLY);
  }
  else return NULL;

  if (fd == -1) return NULL;

  _FILE * fp = (_FILE *)malloc(sizeof(_FILE));
  if (fp == NULL) return NULL;

  fp->fileno = fd;
  fp->flag = FLUSH_LINE;
  fp->out_pos = 0;

  return fp;
}

int _fwrite(_FILE *fp, const char *s, int len)
{
  assert(fp);
  assert(s);

  memcpy(&fp->outbuffer[fp->out_pos], s, len);
  fp->out_pos += len;

  if (fp->flag & FLUSH_NOW)
  {
    write(fp->fileno, fp->outbuffer, fp->out_pos);
    fp->out_pos = 0;
  }
  else if (fp->flag & FLUSH_LINE)
  {
    if (fp->outbuffer[fp->out_pos - 1] == '\n')
    {
      write(fp->fileno, fp->outbuffer, fp->out_pos);
      fp->out_pos = 0;
    }
  }
  else if (fp->flag & FLUSH_ALL)
  {
    if (fp->out_pos == SIZE)
    {
      write(fp->fileno, fp->outbuffer, fp->out_pos);
      fp->out_pos = 0;
    }
  }
  return len;
}

void _fflush(_FILE *fp)
{
  assert(fp);
  if (fp->out_pos > 0)
  {
    write(fp->fileno, fp->outbuffer, fp->out_pos);
    fp->out_pos = 0;
  }
}

void _fclose(_FILE *fp)
{
  assert(fp);
  _fflush(fp);
  close(fp->fileno);
  free(fp);
}
